Phosphorus Recycling for a Sustainable Future

The City of Boise is planning and designing improvements to the West Boise Wastewater Treatment Facility to reduce effluent phosphorus to meet an anticipated 0.20 or 0.07 mg/L phosphorus limitation. An innovative wastewater treatment process that combines the technologies of enhanced biological phosphorus removal with struvite production using anaerobically digested biosolids dewatering filtrate and waste activated sludge phosphate enrichened filtrate as feedstock has been selected. Pilot test results of a fluidized bed struvite reactor were used to calibrate the whole plant process simulator modeling. Impacts of biosolids phosphorus for various treatment process alternatives on soils at the City-owned and City-operated biosolids application site were evaluated utilizing extensive special lab testing. This struvite production process option was found to be the most sustainable since it minimizes consumptive use of chemicals, maximizes recycling of phosphorus, minimizes impacts to the City's biosolids application site, and has a comparable estimated lifecycle cost.